1. Filed of the Invention
The present invention relates to remedies for Parkinson's disease.
More particularly, the present invention relates to an agent for treating and/or preventing Parkinson's disease or Parkinson's syndrome, comprising, as an active ingredient, an astrocyte function-improving agent represented by formula (I), a non-toxic salt thereof or a hydrate thereof: wherein the meaning of each symbol will be defined hereinafter.
2. Discussion of the Background
Parkinson's disease is a neurodegenerative disease which has been designated as one of specialization diseases by the Ministry of Health and Welfare in Japan. Concerning the clinical symptoms of Parkinson's disease, there are observed three large characteristics, i.e., 1) tremor, 2) akinesia and 3) rigidity. Since it was found that the dopamine content was reduced in the brain of patients with Parkinson's disease, it is considered that a decrease in dopamine in the brain causes Parkinson's disease. Therefore, the treatment of Parkinson's disease is carried out by administering dopamine with a form of precursor, regulating the dopamine metabolism or using dopamine agonist.
There have been known several remedies for Parkinson's disease, and typical examples include L-dopa (dopamine precursor), dopamaine agonists, anticholinergic drugs, dopamine release promoters (amantadine etc.) and monoamine oxidase B inhibitors (selegiline etc.). However, these drugs suffer from some problems, such as a decline of the drug effect after prolonged administration, side effects, a failure to prevent the progress of the disease and the like, and thus therapeutic benefit obtained with antiparkinsonian drugs available at present is insufficient.
Parkinson's syndrome means a group of nervous diseases including Parkinson's disease which exhibit conditions similar to Parkinson's disease (i.e., the three symptoms as described above).
On the other hand, it is stated in JP-A-7-316092 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) that compounds represented by formula (I) have effects of improving brain functions (in particular, astrocyte function) and therefore are useful in treating and preventing Alzheimer's disease, amyotrophic lateral sclerosis, progressive supranuclear palsy, olivopontocerebellar atrophy, neuronal dysfunction by stroke or traumatic injury, multiple sclerosis, astrocytoma, meningitis, brain abscess, Creutzfeldt-Jakob disease, AIDS dementia etc.